The present invention relates to power generation and more particularly to improved control systems and methods for converting alternating current (AC) power to direct current (DC) power.
AC generators convert mechanical energy, which can be produced by gasoline or diesel motors, into electrical energy. Since AC generators convert mechanical energy generated by gasoline and diesel motors into electrical energy and gasoline or diesel motors are easy to operate as stand alone units, portable generators typically include an AC generator connected to a gasoline or diesel motor. Since many devices are configured to run on DC power, the AC power generator can be configured with an inverter/rectifier which converts AC power to DC power.
Some applications require DC power sources that have a stable regulated voltage. Converting AC power into DC power for these applications can be difficult because the speed of the motor driving the AC generator can vary by several thousand revolutions per minute (rpm), which can significantly affect the output of the AC generator. Since the generator's output AC voltage varies with speed, the AC generator must boost the voltage at the low end of the speed range and reduce the AC voltage at the high end of the speed range to compensate for variations in the motor's speed. Typically, a control algorithm is used to regulate the DC output voltage. These control algorithms usually require that the generator's rotor position be known in order to regulate a high voltage DC output. Traditional systems use a rotor position feedback device (hardware) such as optical encoders or mechanical sensors to obtain the rotor position. However, optical encoders and mechanical sensors have proven to be costly to implement and decrease overall system reliability.
Since a generator's rotor position and sometimes rotor speed, is required as an input to most algorithms that control and regulate the high voltage DC output, and since devices that measure the rotor position or speed are costly and effect reliability, it is difficult to provide a cost effective reliable portable high voltage DC power source. Therefore, what is needed is a system and method for regulating high voltage DC power output that does not rely on using sensors to measure a rotor's position or speed. A generator that does not rely on using sensors to measure the rotor's position or speed will be more cost effective and have increased reliability because of the elimination of sensors and related design elements.